On Feb 3, 2007, at 02:31, dudekula mastan wrote:
After creating the ZFS file system on a VTOC labeled disk, I am
seeing the following warning messages.
Feb 3 07:47:00 scoobyb Corrupt label; wrong magic number
Feb 3 07:47:00 scoobyb scsi: [ID 107833 kern.warning] WARNING: /
scsi_vhci/[EMAIL PROTECTED] (ssd156):
Any idea on this ?
This generally means that this device doesn't have a label - and this
particular device would be the multipathed device identified by the
GUID 600508b400102eb700012000004b0000 or the old BSD style driver
enumeration ssd156 .. (take a look at http://access1.sun.com/
codesamples/disknames.html to see an example on how to use libdevinfo
to convert this to the SVR4 c#t#d# style name)
Now with ZFS if you don't specify a slice, you're essentially asking
ZFS to use and autolabel the entire disk which will put an EFI style
label on since the older sun style VTOC labels have an upper limit of
1TB per disk (EFI should work up to 2^64 LBAs.) The older sun VTOC
labels typically use slice 2 as a backup to show the entire disk and
will store the label in the first 512B, whereas the EFI labels will
use 34 sectors at the start of the disk to store the label, and will
also reserve a portion at the tail end of the disk for a backup label.
With the older sun style VTOC labels, if you ever overwrite the first
the first 512B on cylinder 0 of the disk (eg: dd if=/dev/zero of=/dev/
rdsk/c1t1d0s2 where s2 is the typical backup label starting at
cylinder 0) you'll overwrite the label, whereas with the EFI label
you have to overwrite both protected sections of the disk.
So to reiterate what Robert and Tomas have already gone into .. if
you plan on using the entire disk and want the vdev benefits (the
ability to import/export pools, write caching, etc) you should
probably not specify a slice and allow ZFS to autolabel the disk as
it sees fit.
hth
----
.je
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